1. Field of the Invention
The present invention relates to a receiving circuit and a method for receiving an amplitude shift keying signal and to a use.
2. Description of the Background Art
Amplitude shift keying (ASK) is also called ASK modulation. It is a type of digital modulation. Here, the amplitude of the carrier signal is changed to transmit different values, for example, a zero and a one or a word with several bits.
German Patent Application No. DE 10 2006 005 032 A1, which corresponds to U.S. Publication No. 20070194959, discloses a receiving method with digital level adjustment by a first correction factor in the analog section and an incremental level change in the digital section.
German Patent No. DE 692 24 925 T2, which corresponds to U.S. Pat. No. 5,230,099, shows a system for controlling phase and gain errors in a direct conversion I/Q receiver. In this case, I and Q baseband signal components, which are in quadrature, are generated. These signals are then independently filtered and amplified at a low frequencies on separate signal channels. The I and Q components formed as a result of the mixing process allow the signal to be conveniently demodulated. The system operates by generating new I′ and Q′ signals on the basis of the I and Q baseband components. The I′ and Q′ signals are formed so that the cos(2 phi) and sin(2 phi) correspond, where phi represents the phase angle of which the original I and Q components are a function. The I′ and Q′ signals are then normalized with respect to signal amplitude to produce I″ and Q″ signals, which are independent of amplitude effects. The thus resulting I″ and Q″ signals are then filtered to generate DCI and DCQ signals which correspond to their DC components. The DC components DCI and DCQ correlate with the gain and phase errors in the receiver, so that gain and phase error correction is possible. A plurality of multipliers and adders are provided for forming the correction function.